1. Field of Invention
The present invention related to a method and apparatus for providing multicast and/or broadcast service optimisations in wireless LAN networks, including that set forth in IEEE 802.11.
2. Description of Related Art
The problem with the current multicast service scheme in IEEE 802.11 networks is related to power save functionality. The base standard defines fixed power save scheme to be used by broadcast and different multicast services. The scheme basically defines a fixed listen interval for the non-AP STAs. The AP will buffer all the broadcast and multicast traffic and after specific DTIM Beacon frame (DTIM is every nth Beacon frame) it will deliver automatically all the buffered broadcast and multicast traffic. The problem here is that different broadcast and multicast services may have very different service characteristic and having only one static scheme in WLAN level is not flexible enough. The services may vary from very basic IP level broadcast services like Address Resolution Protocol (ARP) or Dynamic Host Configuration Protocol (DHCP), which typically have low bit rates with relaxed delay requirements, to different multicast streaming services (audio, video, . . . ) having high bit rate requirements and more strict real time requirements.
In effect, with WLAN multicast service enhancement, there can be different services: others like ARP are creating IP connectivity for the terminal. These protocols are running in the background all the time. When the terminal is inactive, in stand by state, the power consumption to receive data from these protocols defines the stand by power consumption. These protocols require long multicast/broadcast listen intervals, in order to reduce activity periods and power consumption. Some applications, like audio and video services, need short multicast listening intervals in order to meet QoS and delay requirements.
Currently, the AP can indicate that there is buffered broadcast or multicast data with the same single bit. This causes the terminals to listen to the multicast data even though they would not be receiving any themselves.